US3813549A - Self-healing electrode for uniform negative corona - Google Patents

Self-healing electrode for uniform negative corona Download PDF

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Publication number
US3813549A
US3813549A US00317973A US31797372A US3813549A US 3813549 A US3813549 A US 3813549A US 00317973 A US00317973 A US 00317973A US 31797372 A US31797372 A US 31797372A US 3813549 A US3813549 A US 3813549A
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US
United States
Prior art keywords
valve metal
tantalum
coating
wire
electrode
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00317973A
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English (en)
Inventor
Stefano T Di
R Laibowitz
R Rosenberg
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International Business Machines Corp
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International Business Machines Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by International Business Machines Corp filed Critical International Business Machines Corp
Priority to US00317973A priority Critical patent/US3813549A/en
Priority to GB5149373A priority patent/GB1438995A/en
Priority to CA185,521A priority patent/CA1087241A/en
Priority to FR7341680A priority patent/FR2211775B1/fr
Priority to JP13491473A priority patent/JPS5326970B2/ja
Priority to DE2363088A priority patent/DE2363088B2/de
Priority to IT44837/73A priority patent/IT1001174B/it
Application granted granted Critical
Publication of US3813549A publication Critical patent/US3813549A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/02—Apparatus for electrographic processes using a charge pattern for laying down a uniform charge, e.g. for sensitising; Corona discharge devices
    • G03G15/0291—Apparatus for electrographic processes using a charge pattern for laying down a uniform charge, e.g. for sensitising; Corona discharge devices corona discharge devices, e.g. wires, pointed electrodes, means for cleaning the corona discharge device
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05F—STATIC ELECTRICITY; NATURALLY-OCCURRING ELECTRICITY
    • H05F3/00—Carrying-off electrostatic charges
    • H05F3/04—Carrying-off electrostatic charges by means of spark gaps or other discharge devices

Definitions

  • the present invention relates to electrodes used for charging electrophotographic image surfaces in copying machines. More particularly, the disclosure is directed to the negative corona discharge electrodes which produce a negative charge that is applied to the photoconductive surface exposed to the corona discharge.
  • the electrode structure includes a combination of a wire of valve metal with a high resistivity coating spread uniformly over the surface of the wire.
  • the valve metal, one example being tantalum, may serve as-the electrode wire itself or may surround an inner wire such as stainless steel.
  • the plasma glow produced will spread uniformly along the length of the wire.
  • a valve metal which forms a hard oxide under the high resistivity coating, the electrode is selfhealing in that if cracks or imperfections occur in the coating, the exposed valve metal will oxidize and fill in the cracks and imperfections.
  • the present invention relates to the field of electrographic imaging and more particularly to an improved electrode for generating a negative corona discharge for electrographic imaging.
  • Electrographic image copier systems employ negative discharge corona electrodes to produce a negative charge on a photoconductive surface.
  • the electrode is normally a conductive wire which inherently produces a non-uniform corona discharge along its length resulting in streaks and other imperfections in the resultant visible copy.
  • An object of the present invention is to provide an electrode for producing a uniform homogeneous negative corona discharge.
  • Another object of the present invention is to provide a negative corona-discharge which is self-healing in the event that cracks and imperfections occur.
  • Still another object of the present invention is to provide a negative corona discharge electrode which includes a valve metalhaving a uniform high resistivity coating.
  • FIG. I is a schematic drawing illustrating the field distribution along the length of a typical prior art corona electrode wire which is suspended above a ground employed in an electrophotographic copying machine.
  • negative corona discharge is used in many types of electrographic image copying machines.
  • the negative corona discharge is used to apply a negative charge pattern on a photoconductive surface to form an electrostatic latent image.
  • the latent electrostatic image is used in combination with the deposition of electroscopic material to form a visible image.
  • a problem with this technology is that the corona around the discharge electrode is often inhomogeneous along the length of the electrode wire due to nonuniformity of the wire. This in turn results in an inhomogeneous corona and non-uniform charging of the photoconductive surface and produces streaks and im perfections in the final visible copy.
  • the non-uniformity of the corona discharge results from distortions of the electric field around the electrode wire caused by charge clouds.
  • the discharge is initiated by the field-induced injection of electrons from the wire into space.
  • FIG. 1 a schematic drawing is shown illustrating the field distribution along the length of a typical prior art corona electrode wire 10 which is suspended above a ground plane 12.
  • the electrons, positive ions and negative ions are represented as indicated in the drawing.
  • the negative ions formed by the discharge drift slowly from wire l0'to the collecting electrode (ground plane 12) as represented in FIG. 1.
  • a negative ion cloud 14 forms an electrostatic shield covering alength of the wire 10.
  • Corona glow does not appear over most of the shielded region because of a reduced surface field at the wire.
  • the equipotential lines are distorted as shown in F IG. 1, a plasma glow is found at the point of electron injection into the corona.
  • the field free region of the plasma glow therefore, acts to enhance the field at the point of electron injection and to continue the injection at that point.
  • this regenerative process produces corona discharge at several small points along the wire with dark spaces between them as indicated by the designations high field and low field.
  • the points of corona migrate along the wire until they stabilize at regions where conditions, on the wire surface facilitate discharge.
  • anelectrode wire with a uniform resistive coating
  • the resistive coating acts as a limiting resistor which decreases the surface field at'the points of high current injection. If the coating has a sufficiently high resistivity, any point of high injection current will be less favorable to corona discharge than the surrounding dark regions. Therefore, the corona glow 16 will spread to cover the entire wire uniformly. This mechanism is illustrated in FIG. 2.
  • FIG. 2 there is schematically shown a field distribution along the length of a corona wire 18 which is uniformly coated with a material 20 of high electrical resistance. An electrical field across coating material 20 at the point of injection lowers the surface field at that point.
  • FIG. 2 what is shown in FIG. 2 is a set of equipotential surfaces around a point of high current injection.
  • Potential drop across the resistive coating 20 at the corona point (the corona glow is indicated by reference numeral 22) lowers the surface field at that point of the electrode wire.
  • the coating 20 must be uniform and free of cracks and imperfections to function properly. In the present invention, if any cracks or imperfections occur, self-healing of the crackedareas is produced by a plasma enhanced oxidation of the chemically active valve metal which is found under the resistive coating 20. .
  • the metallic wire underlayer 18 will plasma oxidize when exposed to the corona discharge to form a resistive patch in the coating layer.
  • the resistive surface coating should have a high resistivity, for example, greater than ohms per centimeter. Also, the resistive surface should be initially amorphous and crack resistant. The resistive coating 20 should also be a material that will not sputter easily, so that the coating will not be eroded during operation.
  • the electrode wire 18 should be an active valve metal such that a self-healing oxide will form in any cracks, imperfections or damaged areas which may occur in resistive coating 20 in order to restore uniformity.
  • the corona electrode may be as shown in FIG. 2 wherein the electrode wire 18 is a valve metal selected from the representative group including tantalum, niobium, zirconium, hafnium, bismuth, tungsten and antimony, and any other hard, active valve metals which plasma oxidize to produce a resistive oxide for self-healing purposes.
  • the electrode wire 18 is a valve metal selected from the representative group including tantalum, niobium, zirconium, hafnium, bismuth, tungsten and antimony, and any other hard, active valve metals which plasma oxidize to produce a resistive oxide for self-healing purposes.
  • the aforesaid valve metals may be used separately or in combination.
  • the corona electrode is formed by selecting the valve metal, i.e., tantalum, for wire element 18 which may have a diameter in the order of 0.005 inches.
  • the tantalum wire 18 is then anodized to form an oxide (Ta O of thickness in the order of 1,000 Angstroms using an anodize-etch repeat technique wherein the tantalum is placed under tension-in a suitable electrolyte with a potential applied between the wire and a cathode to produce the oxide.
  • the resultant oxide is removed by etching and then the anodizing-etching steps are repeated until an oxide surface is formed on the tantalum wire having desired uniformity.
  • the final anodization of the tantalum wire is achieved by connecting the two electrodes of the electrolytic cell (the wire and the cathode) through a constant current source to achieve the desired final thickness of the high resistive oxide coating 20.
  • the electrode wire 18 may also consist of an inner core of stainless steel, hardened steel, or tungsten surrounded by one of the aforesaid valve metals such as tantalum, to provide a three-layer structure.
  • the corona electrode structure may be composed such that the uniform high resistivity coating 20 is formed of amorphous, semiinsulating layers of insulating polymers, silicon nitride (Si N or silicon dioxide (SiO deposited on a wire with a valve metal surface, such as tantalum.
  • FIG. 3 a plan view is shown illustrating a structure wherein a plurality of corona discharge electrodes as illustrated in FIG. 2 are arrayed in parallel to form an apparatus which may be used in an electrostatic copying machine.
  • An electrode means adapted for producing a corona discharge comprising an inner core wire of valve metal surrounded by an outer uniform coating of the oxide of said valve metal wherein said valve metal is selected from the group consisting of tantalum, niobium, zirconium, hafnium, bismuth, and antimony.
  • valve metal is tantalum and said high resistivity material of said outer coating comprises anodized tantalum oxide.
  • valve metal surrounds a high tensile strength core wire.
  • An electrode means adapted for producing a corona discharge comprising an inner core wire of valve metal surrounded by an outer uniform coating of high resistivity material, said-outer coating being selected from the group consisting of an oxide of said valve metal, silicon nitride, silicon dioxide and an insulating polymer, wherein said valve metal is selected from the group consisting of tantalum, niobium, zirconium, hafnium, bismuth, and antimony.
  • said inner core metal is tantalum and said uniform coating of high resistivity material is an amorphous semiinsulating coating selected from the group consisting of silicon nitride Si N silicon dioxide SiO and insulating polymers.
  • An electrode means adapted for producing a corona discharge comprising an inner core wire of tantalum surrounded by an outer uniform coating of the oxide of tantalum wherein said tantalum of said outer coating comprises an anodized tantalum oxide film about 1,000 Angstroms thick.
  • An electrode means adapted for producing a corona discharge comprising an inner core wire of valve metal surrounded by an outer uniform coating of high resistivity material, said outer coating being selected from the group consisting of a silicon nitride, silicon dioxide and an insulating polymer, wherein said valve metal is selected from the group consisting of tantalum,
  • niobium zirconium, hafnium, bismuth, and antimony.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • General Physics & Mathematics (AREA)
  • Electrostatic Charge, Transfer And Separation In Electrography (AREA)
  • Elimination Of Static Electricity (AREA)
US00317973A 1972-12-26 1972-12-26 Self-healing electrode for uniform negative corona Expired - Lifetime US3813549A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
US00317973A US3813549A (en) 1972-12-26 1972-12-26 Self-healing electrode for uniform negative corona
GB5149373A GB1438995A (en) 1972-12-26 1973-11-06 Corona discharge electrode
CA185,521A CA1087241A (en) 1972-12-26 1973-11-09 Self-healing electrode for uniform negative corona
FR7341680A FR2211775B1 (enrdf_load_stackoverflow) 1972-12-26 1973-11-14
JP13491473A JPS5326970B2 (enrdf_load_stackoverflow) 1972-12-26 1973-12-04
DE2363088A DE2363088B2 (de) 1972-12-26 1973-12-19 Koronaentladungselektrode zur Erzeugung einer negativen Koronaentladung
IT44837/73A IT1001174B (it) 1972-12-26 1973-12-20 Elettrodo perfezionato per carica re superfici di immagini elettro fotografiche in macchine per copia re

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US00317973A US3813549A (en) 1972-12-26 1972-12-26 Self-healing electrode for uniform negative corona

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US3813549A true US3813549A (en) 1974-05-28

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US00317973A Expired - Lifetime US3813549A (en) 1972-12-26 1972-12-26 Self-healing electrode for uniform negative corona

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US (1) US3813549A (enrdf_load_stackoverflow)
JP (1) JPS5326970B2 (enrdf_load_stackoverflow)
CA (1) CA1087241A (enrdf_load_stackoverflow)
DE (1) DE2363088B2 (enrdf_load_stackoverflow)
FR (1) FR2211775B1 (enrdf_load_stackoverflow)
GB (1) GB1438995A (enrdf_load_stackoverflow)
IT (1) IT1001174B (enrdf_load_stackoverflow)

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4542977A (en) * 1982-09-20 1985-09-24 Konishiroku Photo Industry Co., Ltd. Method and apparatus for separating recording paper from image retaining member
US4585321A (en) * 1984-10-30 1986-04-29 Kabushiki Kaisha Toshiba Corona discharging apparatus
US4587527A (en) * 1985-05-15 1986-05-06 Eastman Kodak Company Charging electrodes bearing a doped semiconductor coating
US4910637A (en) * 1978-10-23 1990-03-20 Rinoud Hanna Modifying the discharge breakdown
US5087856A (en) * 1989-06-19 1992-02-11 Ricoh Company, Ltd. Discharge electrode having a thin wire core and surface coating of amorphous alloy for a discharger
US20100312294A1 (en) * 2008-04-30 2010-12-09 Medtronic, Inc. Medical device with self-healing material
US20140216343A1 (en) 2008-08-04 2014-08-07 Agc Flat Glass North America, Inc. Plasma source and methods for depositing thin film coatings using plasma enhanced chemical vapor deposition
WO2016089427A1 (en) * 2014-12-05 2016-06-09 Agc Flat Glass North America, Inc. Plasma source utilizing a macro-particle reduction coating and method of using a plasma source utilizing a macro-particle reduction coating for deposition of thin film coatings and modification of surfaces
US9721764B2 (en) 2015-11-16 2017-08-01 Agc Flat Glass North America, Inc. Method of producing plasma by multiple-phase alternating or pulsed electrical current
US9721765B2 (en) 2015-11-16 2017-08-01 Agc Flat Glass North America, Inc. Plasma device driven by multiple-phase alternating or pulsed electrical current
US10242846B2 (en) 2015-12-18 2019-03-26 Agc Flat Glass North America, Inc. Hollow cathode ion source
US10573499B2 (en) 2015-12-18 2020-02-25 Agc Flat Glass North America, Inc. Method of extracting and accelerating ions
US10586685B2 (en) 2014-12-05 2020-03-10 Agc Glass Europe Hollow cathode plasma source

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1554266A (en) * 1975-07-14 1979-10-17 Xerox Corp Corona charging device
US4057723A (en) * 1976-01-23 1977-11-08 Xerox Corporation Compact corona charging device
US4227234A (en) 1978-07-03 1980-10-07 Xerox Corporation Corona charging element
DE2855864A1 (de) * 1978-12-22 1980-07-10 Ibm Deutschland Ionenquelle, insbesondere fuer ionenimplantationsanlagen
JPH02291574A (ja) * 1989-04-28 1990-12-03 Ricoh Co Ltd 放電電極用細線

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3075078A (en) * 1960-05-13 1963-01-22 Rca Corp Corona device
US3133193A (en) * 1962-01-22 1964-05-12 Du Pont Corona discharge apparatus for the surface treatment of plastic resins
US3281347A (en) * 1962-07-13 1966-10-25 Int Paper Co Method and apparatus for treating plastic coated paper
US3566108A (en) * 1967-01-27 1971-02-23 Xerox Corp Corona generating electrode structure for use in a xerographic charging method
US3612864A (en) * 1968-01-13 1971-10-12 Yasuo Tamai Imaging system utilizing an electrode treated with a mixture of a hygroscopic material and a hydrophilic binder

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE793227A (fr) * 1971-12-23 1973-06-22 Xerox Corp Generateur d'effet corona et procede de production de celui-ci

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3075078A (en) * 1960-05-13 1963-01-22 Rca Corp Corona device
US3133193A (en) * 1962-01-22 1964-05-12 Du Pont Corona discharge apparatus for the surface treatment of plastic resins
US3281347A (en) * 1962-07-13 1966-10-25 Int Paper Co Method and apparatus for treating plastic coated paper
US3566108A (en) * 1967-01-27 1971-02-23 Xerox Corp Corona generating electrode structure for use in a xerographic charging method
US3612864A (en) * 1968-01-13 1971-10-12 Yasuo Tamai Imaging system utilizing an electrode treated with a mixture of a hygroscopic material and a hydrophilic binder

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4910637A (en) * 1978-10-23 1990-03-20 Rinoud Hanna Modifying the discharge breakdown
US4542977A (en) * 1982-09-20 1985-09-24 Konishiroku Photo Industry Co., Ltd. Method and apparatus for separating recording paper from image retaining member
US4585321A (en) * 1984-10-30 1986-04-29 Kabushiki Kaisha Toshiba Corona discharging apparatus
US4587527A (en) * 1985-05-15 1986-05-06 Eastman Kodak Company Charging electrodes bearing a doped semiconductor coating
US5087856A (en) * 1989-06-19 1992-02-11 Ricoh Company, Ltd. Discharge electrode having a thin wire core and surface coating of amorphous alloy for a discharger
US20100312294A1 (en) * 2008-04-30 2010-12-09 Medtronic, Inc. Medical device with self-healing material
US8442651B2 (en) 2008-04-30 2013-05-14 Medtronic, Inc. Medical device with self-healing material
US9478401B2 (en) 2008-08-04 2016-10-25 Agc Flat Glass North America, Inc. Plasma source and methods for depositing thin film coatings using plasma enhanced chemical vapor deposition
US20150004330A1 (en) 2008-08-04 2015-01-01 Agc Flat Glass North America, Inc. Plasma source and methods for depositing thin film coatings using plasma enhanced chemical vapor deposition
US20150002021A1 (en) 2008-08-04 2015-01-01 Agc Flat Glass North America, Inc. Plasma source and methods for depositing thin film coatings using plasma enhanced chemical vapor deposition
US20140216343A1 (en) 2008-08-04 2014-08-07 Agc Flat Glass North America, Inc. Plasma source and methods for depositing thin film coatings using plasma enhanced chemical vapor deposition
US10580624B2 (en) 2008-08-04 2020-03-03 Agc Flat Glass North America, Inc. Plasma source and methods for depositing thin film coatings using plasma enhanced chemical vapor deposition
US10438778B2 (en) 2008-08-04 2019-10-08 Agc Flat Glass North America, Inc. Plasma source and methods for depositing thin film coatings using plasma enhanced chemical vapor deposition
US10580625B2 (en) 2008-08-04 2020-03-03 Agc Flat Glass North America, Inc. Plasma source and methods for depositing thin film coatings using plasma enhanced chemical vapor deposition
WO2016089427A1 (en) * 2014-12-05 2016-06-09 Agc Flat Glass North America, Inc. Plasma source utilizing a macro-particle reduction coating and method of using a plasma source utilizing a macro-particle reduction coating for deposition of thin film coatings and modification of surfaces
US11875976B2 (en) 2014-12-05 2024-01-16 Agc Flat Glass North America, Inc. Plasma source utilizing a macro-particle reduction coating and method of using a plasma source utilizing a macro-particle reduction coating for deposition of thin film coatings and modification of surfaces
US10755901B2 (en) 2014-12-05 2020-08-25 Agc Flat Glass North America, Inc. Plasma source utilizing a macro-particle reduction coating and method of using a plasma source utilizing a macro-particle reduction coating for deposition of thin film coatings and modification of surfaces
US10586685B2 (en) 2014-12-05 2020-03-10 Agc Glass Europe Hollow cathode plasma source
US9721764B2 (en) 2015-11-16 2017-08-01 Agc Flat Glass North America, Inc. Method of producing plasma by multiple-phase alternating or pulsed electrical current
US10559452B2 (en) 2015-11-16 2020-02-11 Agc Flat Glass North America, Inc. Plasma device driven by multiple-phase alternating or pulsed electrical current
US20170309458A1 (en) 2015-11-16 2017-10-26 Agc Flat Glass North America, Inc. Plasma device driven by multiple-phase alternating or pulsed electrical current
US9721765B2 (en) 2015-11-16 2017-08-01 Agc Flat Glass North America, Inc. Plasma device driven by multiple-phase alternating or pulsed electrical current
US10573499B2 (en) 2015-12-18 2020-02-25 Agc Flat Glass North America, Inc. Method of extracting and accelerating ions
US10242846B2 (en) 2015-12-18 2019-03-26 Agc Flat Glass North America, Inc. Hollow cathode ion source

Also Published As

Publication number Publication date
DE2363088B2 (de) 1975-11-27
JPS5326970B2 (enrdf_load_stackoverflow) 1978-08-05
DE2363088A1 (de) 1974-07-11
JPS4991652A (enrdf_load_stackoverflow) 1974-09-02
CA1087241A (en) 1980-10-07
FR2211775A1 (enrdf_load_stackoverflow) 1974-07-19
FR2211775B1 (enrdf_load_stackoverflow) 1976-11-19
IT1001174B (it) 1976-04-20
GB1438995A (en) 1976-06-09

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